Dual in-line packaging with improved moisture resistance

Abstract

A dual in-line packaging comprises a substrate having a top surface, a bottom surface and a peripheral surface, semiconductor chips mounted on the top and bottom surfaces of the substrate, a plurality of terminals fixed to the substrate and projecting from the bottom surface of the substrate, a first layer made of a first material and covering the bottom surface of the substrate and the semiconductor chips, and a second layer made of a second material and covering the top surface of the substrate and the semiconductor chips. The first material is resilient and moisture resistant and the second material is hard compared to the first material.

What is claimed is: 
     
       1. A dual in-line packaging comprising: a substrate having a top surface, a bottom surface and a peripheral surface;   semiconductor chips mounted on the top and bottom surfaces of said substrate;   a plurality of terminals fixed to said substrate and projecting from the bottom surface of said substrate;   a first layer made of a first material and covering the bottom surface of said substrate and bottom surface mounted semiconductor chips, wherein a portion of said first layer is in direct contact with the bottom surface of the substrate, and wherein said first layer has side portions having inner surfaces in direct contact with said substrate peripheral surface; and   a second layer made of a second material and covering the top surface of said substrate and top surface mounted semiconductor chips, wherein a portion of said second layer is in direct contact with the top surface of the substrate, and wherein said second layer has side portions having inner surfaces in direct contact with outer surfaces of said first layer side portions,   said first material being resilient and moisture resistant, said second material being hard compared to said first material, said terminals being arranged in-line along parallel sides of said substrate and penetrating through said first layer to thereby maintain the moisture resistance of said duel in-line packaging even when an external force is applied to said terminals.   
     
     
       2. The dual in-line packaging as claimed in claim 1 wherein said terminals respectively have a stress absorbing portion for absorbing a stress which is generated when the terminals are deformed by an external force. 
     
     
       3. The dual in-line packaging as claimed in claim 2 wherein said terminals respectively have an approximately U-shaped portion which sandwiches a side portion of said substrate, and said stress absorbing portion has an approximately L-shape which connects to said U-shaped portion. 
     
     
       4. The dual in-line packaging as claimed in claim 1 wherein said first material is a silicone resin, and said second material is a phenolic resin which contains glass fiber. 
     
     
       5. The dual in-line packaging as claimed in claim 1 wherein said first material is selected from a group which includes polyurethane, polyurethane rubber, silicon rubber and flexible epoxy. 
     
     
       6. The dual in-line packaging as claimed in claim 1 wherein said second material is selected from a group which includes melamine resin and epoxy resin containing fiber glass. 
     
     
       7. The dual in-line packaging as claimed in claim 1 wherein said substrate is made of a material selected from a group which includes ceramics and glass epoxy. 
     
     
       8. The dual in-line packaging as claimed in claim 1 wherein said first layer further covers the peripheral surface of said substrate, and said second layer further covers a portion of said first layer covering the peripheral surface of said substrate. 
     
     
       9. A dual in-line packaging, comprising: a substrate having a top surface, a bottom surface and a peripheral surface;   semiconductor chips mounted on the top and bottom surfaces of said substrate;   a plurality of terminals fixed to said substrate and projecting from the bottom surface of said substrate;   a first layer made of a first material and covering the bottom surface of said substrate and bottom surface mounted semiconductor chips, wherein said first layer includes side portions having inner surfaces in direct contact with said peripheral surface of said substrate, wherein a portion of said first layer is in direct contact with the bottom surface of the substrate; and   a second layer made of a second material and covering the top surface of said substrate and top surface mounted semiconductor chips, wherein said second layer includes side portions having inner surfaces in direct contact with outer surfaces of said first layer side portions, wherein a portion of said second layer is in direct contact with the top surface of the substrate,   said first material being resilient and moisture resistant, said second material being hard compared to said first material, said terminals being arranged in-line along parallel sides of said substrate and penetrating through said first layer to thereby maintain the moisture resistance of said dual in-line packaging even when an external force is applied to said terminals.   
     
     
       10. A dual in-line packaging, comprising: a substrate having a top surface, a bottom surface and a peripheral surface;   semiconductor chips mounted on the top and bottom surfaces of said substrate;   a plurality of terminals fixed to said substrate and projecting from the bottom surface of said substrate;   a first layer made of a first material and covering the bottom surface of said substrate and bottom surface mounted semiconductor chips, wherein said first layer includes side portions having inner surfaces in direct contact with said peripheral surface of said substrate, wherein a portion of said first layer is in direct contact with the bottom surface of the substrate; and   a second layer made of a second material and covering the top surface of said substrate and top surface mounted semiconductor chips, wherein said second layer includes side portions having inner surfaces in direct contact with outer surfaces of said first layer side portions, wherein a portion of said second layer is in direct contact with the top surface of the substrate,   said first material being resilient and moisture resistant, said second material being hard compared to said first material, said second layer having a substantial quantity of fiber glass so as: (a) to provide an adherence between said side portions of said first and second layers to prevent moisture from entering therebetween, and (b) to have the coefficient of thermal expansion of said second layer be similar to that of said substrate to thereby prevent the generation of thermal stress and cracks in said second layer, said terminals being arranged in-line along parallel sides of said substrate and penetrating through said first layer to thereby maintain the moisture resistance of said dual in-line packaging even when an external force is applied to said terminals.